Postnatal administration of large concentrations of monosodium glutamate (MSG) is known to produce lesions in the arcuate nucleus of the hypothalamus. The effects of intermediate doses of MSG given neonatally on bahavioral and neurological functioning of adults are being studied in this laboratory so as to generate a profile of effects from a known neurotoxicant. Such information will provide a basis for mechanistic studies with environmental neurotoxicants.